Backrest shell for chair



FIG. 1 is a perspective view of top, front and right side of a backrest shell for chair showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a right side view thereof, the left side view being mirror image thereof; and,

FIG. 7 is a cross sectional view at 7-7 shown in FIG. 2 thereof. 

The ornamental design for a backrest shell for chair, as shown and described. 